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用APEX-SZ对子弹团（1 E 0657-56）的Sunyaev-Zel'dovich效应观测

Sunyaev-Zel'dovich Effect Observations of the Bullet Cluster (1E 0657-56) with APEX-SZ

N. W. Halverson, T. Lanting, P. A. R. Ade, K. Basu, A. N. Bender, B. A. Benson, F. Bertoldi, H. -M. Cho, G. Chon, J. Clarke, M. Dobbs, D. Ferrusca, R. Guesten, … 展开作者

N. W. Halverson, T. Lanting, P. A. R. Ade, K. Basu, A. N. Bender, B. A. Benson, F. Bertoldi, H. -M. Cho, G. Chon, J. Clarke, M. Dobbs, D. Ferrusca, R. Guesten, W. L. Holzapfel, A. Kovacs, J. Kennedy, Z. Kermish, R. Kneissl, A. T. Lee, M. Lueker, J. Mehl, K. M. Menten, D. Muders, M. Nord, F. Pacaud, T. Plagge, C. Reichardt, P. L. Richards, R. Schaaf, P. Schilke, F. Schuller, D. Schwan, H. Spieler, C. Tucker, A. Weiss, O. Zahn

备注：
17 pages, 5 figures, accepted for publication in the Astrophysical Journal. Changes in v2: Modified in response to referee comments. Also, improvements in the analysis pipeline and flux calibration result in modification of the maps and model fit parameters. Calibration section and X-ray comparison sections are significantly modified
发表信息：
Astrophys.J.701:42-51,2009
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摘要：

本文报道了用APEX-SZ仪器在150 GHz和1arcmin分辨率下对子弹星系团（1 E0657 - 56）中Sunyaev-Zel'dovich效应（SZE）的观测结果。主要结果是在这个大规模的合并星系团的SZE地图。在源位置的中心1弧分半径内，以23西格玛显著性检测群集。SZE地图有一个大致相似的形态，在现有的X射线地图的这个系统，我们没有发现任何证据的SZE发射的无线电或红外源的显着污染。为了使简单的定量比较与来自X射线观测的气体模型的集群，我们适合我们的数据的等温椭圆β模型，尽管这种模型的不足，这个复杂的合并系统。利用X射线的幂律指数β = 1.04 + 0.16 - 0.10，我们得到了核心半径rc =142 +/- 18 arcsec，轴比为0.889 +/- 0.072，中心温度下降为-771 +/- 71 micro-K_CMB，包括+/-5.5%的通量校准不确定度。结合APEX-SZ图和钱德拉X射线观测的投影电子表面密度图，我们确定团簇气体的质量加权温度为T_mg=10.8 +/- 0.9 keV，明显低于一些先前报道的X射线光谱温度。在流体静力学平衡的等温集群气体分布的假设下，我们计算的气体质量分数为长球形和扁球形的几何形状，并发现它是一致的与以前的结果从X射线和弱透镜观测。这项工作是APEX-SZ实验的第一个结果，也是第一个报告的科学结果，来自于一个大型的多路复用超导过渡边缘传感器测辐射热计阵列的观测。

英文摘要：

We present observations of the Sunyaev-Zel'dovich effect (SZE) in the Bullet cluster (1E 0657--56) using the APEX-SZ instrument at 150 GHz with a resolution of 1 arcmin. The main results are maps of the SZE in this massive, merging galaxy cluster. The cluster is detected with 23 sigma significance within the central 1 arcmin radius of the source position. The SZE map has a broadly similar morphology to that in existing X-ray maps of this system, and we find no evidence for significant contamination of the SZE emission by radio or IR sources. In order to make simple quantitative comparisons with cluster gas models derived from X-ray observations, we fit our data to an isothermal elliptical beta model, despite the inadequacy of such a model for this complex merging system. With an X-ray derived prior on the power-law index, beta = 1.04 +0.16 -0.10, we find a core radius r_c =142 +/- 18 arcsec, an axial ratio of 0.889 +/- 0.072, and a central temperature decrement of -771 +/- 71 micro-K_CMB, including a +/-5.5% flux calibration uncertainty. Combining the APEX-SZ map with a map of projected electron surface density from Chandra X-ray observations, we determine the mass-weighted temperature of the cluster gas to be T_mg=10.8 +/- 0.9 keV, significantly lower than some previously reported X-ray spectroscopic temperatures. Under the assumption of an isothermal cluster gas distribution in hydrostatic equilibrium, we compute the gas mass fraction for prolate and oblate spheroidal geometries and find it to be consistent with previous results from X-ray and weak lensing observations. This work is the first result from the APEX-SZ experiment, and represents the first reported scientific result from observations with a large array of multiplexed superconducting transition-edge sensor bolometers.

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